improve accessibility of navbar (#7962)

app/views/layouts/_header.html.erb

@@ -17,9 +17,9 @@
     <div class="collapse navbar-collapse" id="header-navbar-collapse">
       <form class="form-inline mr-3" id="searchform" autocomplete="off">
         <div class="input-group">
-          <input type="text" id="searchform_input" class="form-control search-query typeahead" role="search" qryType="tags" placeholder="<%= t('layout._header.search') %>"  value="<%= params[:query] %>" required>
+          <input aria-label="Enter Search Query" type="text" id="searchform_input" class="form-control search-query typeahead" role="search" qryType="tags" placeholder="<%= t('layout._header.search') %>"  value="<%= params[:query] %>" required>
           <div class="input-group-append">
-            <button class="btn btn-light" type="submit"><i class="fa fa-search"></i></button>
+            <button class="btn btn-light" type="submit" title="Search button" aria-label="Search Button"><i class="fa fa-search"></i></button>
           </div>
         </div>
       </form>
@@ -109,7 +109,7 @@
                   <% if current_user.profile_image == "https://www.gravatar.com/avatar/eb721d116a28f4a4da4ea67340c8ce75" %>
                     <i class="fa fa-user-circle fa-lg" style="color:white;"></i>
                   <% else %>
-                    <img class="rounded-circle" id="profile-photo" style="width:20px; height:20px; margin-right:8px;" src="<%= current_user.profile_image %>" />
+                    <img class="rounded-circle" id="profile-photo" alt="profile-photo" style="width:20px; height:20px; margin-right:8px;" src="<%= current_user.profile_image %>" />
                   <% end %>
                 </div>
               </a>